More often heard than seen, the Black-billed Cuckoo (11-12 inches) is most easily separated from the similar Yellow-billed Cuckoo (Coccyzus americanus) by its solid brown wings, plain under-tail pattern, and all-black bill. Other field marks include a long tail, thin body, and black legs. Male and female Black-billed Cuckoos are similar at all seasons. The Black-billed Cuckoo breeds across much of the northeastern U.S.and southern Canada. All Black-billed Cuckoos spend the winter in South America, although this species’ winter range is poorly known due to its highly secretive nature. Some Black-billed Cuckoos have been found in the western U.S.during the fall migration, likely resulting from navigational errors. Black-billed Cuckoos breed in forests with plentiful undergrowth and clearings, particularly those near water. On migration, this species may be found in habitat similar to that inhabited during the summer months. Wintering Black-billed Cuckoos inhabit humid tropical forest. The diet of this species is composed primarily of large insects, including grasshoppers, cicadas, and caterpillars. Like many cuckoos, the Black-billed Cuckoo spends much of its time hidden in thick vegetation, where it is not easily seen. Lucky birdwatchers may observe this species slinking through the branches of tall trees while foraging for insect prey. Black-billed Cuckoos are primarily active during the day, but like many migratory birds, this species migrates at night.
Black-billed cuckoos are found in the Neartic and Neotropical regions. In the United States they live from the east coast south to Oklahoma, west to Montana and north to Canada. During the non-breeding season, black-billed cuckoos migrate to northern South America, including Venezuela, Columbia and as far south as central Bolivia. These birds also migrate through the southeastern United States and lowland areas of southeastern Mexico in tropical forests, cloud forests, and arid scrub habitats.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
- American Ornithologists' Union, 1998. Check-list of North American Birds. Washington, DC: American Ornithologists' Union.
- Hughes, J. 2001. Black-billed cuckoo : Coccyzus erythropthalmus. Philadelphia, PA: The Birds of North America, Inc..
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Breeding
Regularity: Regularly occurring
Type of Residency: Breeding
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: east-central and southeastern Alberta east to Prince Edward Island and Nova Scotia, south, at least locally, to Montana, southeastern Wyoming, eastern Colorado, north-central Texas, northern Alabama, and the Carolinas (AOU 1998). NON-BREEDING: northern Venezuela and northern Colombia south to central Bolivia (AOU 1998). MIGRATION: southeastern United States, Bermuda, Mexico (mostly Gulf-Caribbean lowlands), and Middle America (AOU 1998).
Black-billed cuckoos weigh from 40 to 65 grams. They are 28 to 31 centimeters in length and have a wingspan of 34 to 40 centimeters. Black-billed cuckoos have slim bodies and possess a long tail. The upper part of the head and body is a grayish-brown, while the entire underside is white. The bill is black and curves downward. Adult black-billed cuckoos have a reddish ring around their eyes.
Juveniles are similar in appearance except that they have a yellowish or buff-colored eye ring. The white underside of the juveniles may be more cream colored and some parts of the wings may be rusty-brown in appearance. Female black-billed cuckoos are somewhat larger in size than the male. Their close relatives, yellow-billed cuckoos, are similar to black-billed cuckoos in terms of body shape and color. The biggest differences between the two are that yellow-billed cuckoos have a yellow lower mandible and reddish-brown wings.
Range mass: 40 to 65 g.
Range length: 28 to 31 cm.
Range wingspan: 34 to 40 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
- Andersson, M. 1995. Evolution of reversed sex roles, sexual size, dimorphism, and mating system in coucals. Biological Journal of the Linnean Society, 54: 173-181.
- National Geographic Society, 1983. Field Guide to the Birds of North America. Washington, DC: National Geographic Society.
- Robbins, C., B. Bruun, H. Zim. 1966. Birds of North America. New York: Western Publishing Company, Inc..
Length: 31 cm
Weight: 51 grams
Differs from the yellow-billed cuckoo (COCCYZUS AMERICANUS) in lacking rufous primaries and lacking an extensively yellow lower mandible.
Black-billed cuckoos are found in wooded areas and wetlands. They are also inhabitants of deciduous forests, where they prefer orchards and thickets, and habitats near natural water, such as a river, stream, or lake. Black-billed cuckoos have sometimes been found in urban and suburban settings on golf courses or in parks.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest ; scrub forest
Other Habitat Features: urban ; suburban ; agricultural ; riparian
Habitat and Ecology
Comments: BREEDING: Assigned to "eastern forest" biogeographical classification by Pyle et al. (1994). Forest edge and open woodland, both deciduous and coniferous, with dense deciduous thickets (AOU 1998). Found in extensive tracts of dry upland woods where it uses the midstory canopy and the overstory canopy for most activities (Legrand and Hamel 1980). High-ground forest, open woodland, thickets, willow (SALIX spp.), alder (ALNUS spp.), aspen (POPULUS spp.), vines (del Hoyo et al. 1997). In northern plains also utilizes prairie shrub thickets and shelterbelts at lower elevations (Dobkin 1994). In Colorado, most observations in urban forests characterized by introduced tree species. Next most common sightings occur in riparian vegetation dominated by cottonwoods (POPULUS spp.) and boxelders (BISON-M 1997).
Nests in groves of trees, forest edges, moist thickets, overgrown pastures; in deciduous or evergreen tree or shrub. Is a low or ground nesting species (Peterjohn et al. 1995). Nest an open cup, average 1.8 meters above ground, but at times almost on the ground and concealed by tall herbage (Bent 1940, Harrison 1978, Spencer 1943).
NON-BREEDING: During migration occurs from tropical evergreen forest to arid subtropical scrub. In New Mexico occurs where stream conditions provide sufficient permanent moisture for the emergent plants or for a narrow band of deciduous trees and shrubs; at low elevation characterized by cottonwood and sycamore (PLATANUS spp.), at mid-elevations by white alder (ALNUS RHOMBIFOLIA) and bigleaf maple (ACER MACROPHYLLUS), and at high elevations by willow (DeGraaf et al. 1991). In Costa Rica, in second growth, scrubby areas, semi-open, forest edge (Stiles and Skutch 1989). Scrub (arid or humid) as well as forest, although most frequently in lowland humid regions (AOU 1998). Generally found from lowlands up to 2000 meters (del Hoyo et al. 1997). Chipley (1976) observed species in remnant subtropical oak woodland at 1800 meters in Colombia.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
A nocturnal neotropical migrant. Migrates regularly through the southeastern United States; irregularly through Mexico and Middle America; and casually west to the Pacific region (AOU 1983). An uncommon transient migrant through Oaxaca, Mexico (Binford 1989). Migrates through Costa Rica late September to early November and April to early May as an uncommon to very rare migrant in lowlands, occasional in Valle Central (Stiles and Skutch 1989). Spring migration records in Florida, April to May; autumn migrants late August to late October. Also a transatlantic vagrant in autumn to western Europe (del Hoyo et al 1997). Adult males arrive earlier than females in spring; adults migrate earlier than juveniles in fall (Herrick 1910).
Black-billed cuckoos are omnivores feeding mainly on large insects, including especially caterpillars, cicadas, katydids, butterflies, grasshoppers, and crickets. They occasionally eat eggs of other birds and rarely eat aquatic larvae and fish. In the summer, they occasionally feed on fruits and seeds. Other food items include moth larvae, fall webworm, beetles, stink bugs, snails, and dragonflies.
Animal Foods: fish; eggs; insects; mollusks; terrestrial worms
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: carnivore (Eats non-insect arthropods, Vermivore); herbivore (Frugivore , Granivore ); omnivore
Comments: Feeds primarily by gleaning insects from leaves of trees and shrubs (Bent 1940, Terres 1980). Makes short sallies or running, hopping dashes to capture prey items (Stiles and Skutch 1989). Eats insects, mainly caterpillars; also katydids, saw-flies, grasshoppers, crickets, beetles, spiders; rarely frogs, small fish, eggs of other birds; berries especially in autumn (Agro 1994, Sealy 1994, Stiles and Skutch 1989, del Hoyo et al. 1997). May be particularly dependent upon forest tent caterpillars (MALACOSOMA DISSTRIA; Sealy 1978).
Black-billed cuckoos are considered brood parasites. They will sometimes lay their eggs in the nests of other black-billed cuckoos. They have also been reported to lay their eggs in the nests of the yellow-billed cuckoos (Coccyzus americanus), chipping sparrows (Spizella passerina), American robins (Turdus migratorius), gray catbirds (Dumetella carolinensis), and wood thrushes (Hylocichla mustelina). There is little information on the effects of this parasitism on the host. Some studies show that black-billed cuckoo nestlings will eject or crowd out the nestlings of the host. Other brood parasites, including yellow-billed cuckoos (Coccyzus americanus) and brown-headed cowbirds (Molothrus ater), have been known to lay their eggs in the nests of black-billed cuckoos.
The only parasitic organism discovered in black-billed cuckoos is a nasal mite, Cytodites therae. However, more studies of this bird are necessary.
Ecosystem Impact: parasite
Species Used as Host:
- chipping sparrows (Spizella passerina)
- gray catbirds (Dumetella carolinensis)
- wood thrushes (Hylocichla mustelina)
- American robins (Turdus migratorius)
- yellow-billed cuckoos (Coccyzus americanus)
- yellow-billed cuckoos (Coccyzus americanus)
- brown cowbirds (Molothrus ater)
- nasal mites (Cytodites therae)
- Pence, D. 1973. the nasal mites of birds from Louisiana. VIII. Additional records and description of a new species (Acarina: Dermanyssidae, Ereynetidae, Epidermoptidae, and Cytoditidae). Journal of Parasitology, 59/5: 874-880.
Predators of adult black-billed cuckoos include hawks and falcons. Nestlings are taken by common grackles (Quiscalus quiscula) and arboreal snakes and arboreal mammals, such as raccoons (Procyon lotor)s. Black-billed cuckoos are usually taken during migration when birds are tired upon arrival or unfamiliar with the terrain. Black-billed cuckoos are seen and caught easily while crossing open areas.
When a predator is near a nest, an adult cuckoo will align its head, neck, and body in a straight line. It will then "Mew" or give a "Cucucu" call. If the predator is not frightened away, the adult cuckoo will fan out its tail, spread its wings, and let out a "cuck-a-ruck" call. The young assume a perpendicular position with their bill pointed up when a predator is nearby. They remain motionless with widely opened eyes until the predator leaves.
- blackbirds (Icteridae)
- common grackles (Quiscalus quiscula)
- hawks (Accipitridae)
- falcons (Falconidae)
- arboreal snakes (Serpentes)
- arboreal mammals, such as raccoons (Procyon lotor)
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
Comments: Appears to presently occur within entire historic breeding range in North America. It is estimated that the majority of occurrences in breeding range are good to excellent. Quality of occurrences along migratory routes and in winter range is unknown.
10,000 to >1,000,000 individuals
Comments: Large range but low numbers; no reliable population estimate. Characterized as "uncommon to fairly common" with a relative abundance in North America of 0.62 (NGS 1987, Sauer et al. 1996).
Breeding densities vary considerably across years, in apparent response to caterpillar outbreaks (Bent 1940, del Hoyo et al. 1997). In winter joins mixed-species feeding flocks (Chipley 1976, del Hoyo et al. 1997).
Life History and Behavior
Black-billed cuckoos mainly use acoustics to communicate with other cuckoos. They can make around six different sounds, each for various social conditions. At the age of 1 to 3 days, the young produce a call similar to the buzzing of an insect followed by a low, barking call at 6 to 7 days old. The most frequently heard call is a fast and rhythmic series of "cu-cu-cu-cu". This call comes in a set of 2 to 5, all at the same pitch. The Croak call sometimes follows the "cu-cu-cu." The Croak call is 5 short, lower pitched notes "Krak-ki-ka-kruk-kruk". The Croak call can also be heard alone. A low, sad call consists of notes in sets of 2 to 4, with no pause in between the "coo-oo-oo". This call may be used when a predator is near. During courtship, females use a "mew" call to excite the males. This call is also heard when feeding the nestlings. When they use the alarm call, black-billed cuckoos let out a quick fragment of notes that sound like "cuck-a-ruck". During winter migration they are usually quiet. Calls are normally heard during the day and at night in midsummer.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
There is little information on the lifespan of black-billed cuckoos. Since 1955, only 26 out of 6,028 banded black-billed cuckoos have been recovered. Four of these were four years old and one was at least five years old.
Status: wild: 5 (high) years.
- de Magalhaes, J., J. Costa, O. Toussaint. 2005. "HAGR: the Human Ageing Genomic Resources" (On-line). Accessed December 12, 2008 at http://genomics.senescence.info/species/entry.php?species=Coccyzus_erythropthalmus.
Lifespan, longevity, and ageing
Male black-billed cuckoos land on a branch near a potential female mate. The male will hold a food item in his mouth. Next, the male will let out a loud "Cucucu" call. If the female is interested she will move to a branch closer to the male. The female will flip her tail up and down while giving a "Mew" call. The female may flick her tail for up to 15 minutes. The male remains quiet and doesn’t move during this time. The male will then hop to the female’s branch and mount the female. Copulation may be performed at uneven times lasting usually 4 to 5 minutes. Afterwards the male will either eat his food item or feed it to the female. These birds are most likely monogamous. They are solitary during the breeding season, but have been observed in pairs during migration.
Mating System: monogamous
Black-billed cuckoos form mated pairs in mid or late May, sometimes not until June. The pair will then gather materials and build a nest. Nests are most commonly made with small twigs that are loosely woven together. The lining of the nest is made up of leaves, pine needles, and empty cocoons. The nest is made in groves of trees and thickets that are well concealed by leaves and tangles of vines. They are placed 1 to 2 meters above the ground. Nests are constructed continuously through incubation. Black-billed cuckoos may also lay their eggs in the nests of other birds, making them brood parasites (see Ecosystem Roles).
Black-billed cuckoos breed as early as May and as late as September, breeding peaks in June and July. The eggs of black-billed cuckoos are elliptical. Egg length is 22.6 to 32.3 mm and width is 18.3 to 23.5 mm. The eggs are greenish-blue and sometimes appear marbled. Black-billed cuckoos generally lay a single egg at 2-day intervals.
It is possible to tell when birds are incubating eggs by observing the lower breast and abdomen, where an incubation patch - or area free of feathers - will develop. The incubation period is 10 to 11 days and both parents are present during incubation, replacing each other at different intervals throughout the day. Hatching occurs in the early morning. The adult may push the shell around the nest. After about five minutes, the nestling will give a low call and leave the shell. The young bird is alert and active within minutes. Hatchlings fledge at about 3 weeks old and begin to search for food around 21 to 24 days old, sometimes accompanied by the adult.
Breeding interval: Breeding occurs once yearly.
Breeding season: Breeding occurs from May through September.
Range eggs per season: 2 to 5.
Range time to hatching: 10 to 11 days.
Average fledging age: 17 days.
Range time to independence: 21 to 24 days.
Average age at sexual or reproductive maturity (female): unknown weeks.
Average age at sexual or reproductive maturity (male): unknown weeks.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Both parents are responsible for building the nest for their eggs. Both parents participate in incubation and brooding. Adults will also spread their wings and tail out to cover the eggs and protect them from rain. Hatchlings are altricial, but they develop quickly and leave the nest within 17 days. Both parents are responsible for feeding young. Adults will crush the food for their young and thrust the food into their mouths. The adults will also shade the chicks from the sunlight. The young expel wastes into sacs after feeding and adults either eat or remove the sacs.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
- Hughes, J. 2001. Black-billed cuckoo : Coccyzus erythropthalmus. Philadelphia, PA: The Birds of North America, Inc..
- Rylander, K., M. Rylander. 2002. The Behavior of Texas Birds. Austin, TX: University of Texas Press.
- Spencer, O. 1943. Nesting Habits of the Black-Billed Cuckoo. The Wilson Bulletin, 55, 1: 11-22.
- Wayne, A. 1911. The Black-Billed Cuckoo (Coccyzus erythrophthalmus) Breeding on the Coast of South Carolina. The Auk, 28, 4: 485-486.
A facultative brood parasite; occasionally lays eggs in the nest of Yellow-billed Cuckoo (COCCYZUS AMERICANUS) and at least ten other passerine species (Bent 1940, Harrison 1979, Hughes 1997, Thomas 1995). Lays clutch of two to five (usually two to three) eggs, mostly May-July. Incubation about 14 days by both parents. Young hatch at intervals, differ in size, and are tended by both parents. Adults bring insects carried in throat pouch and disgorge into mouth of nestlings. Chicks climb on branches at 7-9 days, fly at 21-24 days. Nesting initiation dates and clutch size may be influenced by food availability (Sealy 1978). A small sample of observed nests indicate a nesting success rate of 55 percent and chick survival of 71 percent (Spencer 1943).
Molecular Biology and Genetics
Barcode data: Coccyzus erythropthalmus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
-- end --
Download FASTA File
Statistics of barcoding coverage: Coccyzus erythropthalmus
Public Records: 4
Specimens with Barcodes: 4
Species With Barcodes: 1
Black-billed cuckoos are protected under the United States Migratory Bird Act. They have a declining population that is based on their global abundance, their breeding and winter distribution, and the threats on breeding and wintering grounds. There are 16 states where black-billed cuckoo populations might be in decline: Iowa, Minnesota, Illinois, Indian, Michigan, Ohio, Wisconsin, North Dakota, South Dakota, Massachusetts, Maine, Connecticut, New Hampshire, New Jersey, Rhode Island, and New York.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5B - Secure
Rounded National Status Rank: N5B - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Large range but low numbers. Evidently has declined in central North America, but rangewide trend based on BBS data is stable.
Comments: Loss and degradation of riparian habitats may be the greatest threat to the species in arid areas; water diversion, flood control projects, ground water pumping, livestock grazing, and urbanization are all factors. Tropical deforestation may be a significant threat in winter range. As a nocturnal migrant, faces hazards such as collisions with TV towers and other structures (del Hoyo et al. 1997).
Restoration Potential: In west where declines are most pronounced and significant, may respond to restoration of riparian forest and shrub habitats, particularly in arid areas. May also benefit from shelterbelts, urban forests, and other artificial habitats.
Preserve Selection and Design Considerations: Optimum patch size and aspects of landscape relationship are unknown, but one study suggests that the species is most likely to be found breeding in forest stands of more than 4 hectares in size (Forman et al. 1976). Elsewhere extensive forest stands may be preferred (Legrand and Hamel 1980). In arid and semi-arid portions of its range may be particularly dependent upon riparian forest and shrubby understories for breeding sites and travel corridors.
Management Requirements: Maturation of second growth deciduous and evergreen forests in central and eastern breeding range may enhance habitat quality and increase habitat availability. Management which maintains large trees, wildlife corridors, hedgerows, woodlots, and controls grazing by domestic livestock may be beneficial. Creating water impoundments or reducing perennial stream flow may degrade critical riparian habitats (SIL 1999). Appears to select dense nesting cover at low-canopy levels suggesting a positive response to restrictive grazing regimes. Because of food preference for caterpillars and other large insects, chemical or other control of undesirable insect species or related plants may be adverse.
Management Research Needs: Largely unstudied. More information needed on breeding and foraging ecology, and extent of wintering range and winter habitat parameters. Studies on the relative role of tropical deforestation compared with temperate habitat fragmentation are needed, as is response to various fire, logging, and grazing regimes. As a brood parasite, relationship to host species needs better understanding. Sensitivity to most pesticides unknown, but needs further study because of reportedly strong reproductive response to irruptive insect populations.
Global Protection: Few to several (1-12) occurrences appropriately protected and managed
Comments: Several protected occurrences in North American breeding range. However, information generally lacking on protection of occurrences along corresponding migration routes and wintering areas. No element occurrences are known to be protected along migration routes in Mexico; migratory routes may be adequately protected in forest reserves and national parks in Costa Rica and Belize. Winter distribution and habitat requirements in northern South America poorly defined so adequate global protection of any occurrences is uncertain.
Relevance to Humans and Ecosystems
There are no known adverse effects of black-billed cuckoos on humans.
Black-billed cuckoos help control the population of pest insects through predation. Studies show that following an outbreak of gypsy moths (Lymantria dispar) the density of black-billed cuckoos increases. These birds disappear several years after the outbreak is under control.
Positive Impacts: controls pest population
- Gale, G., J. DeCecco, M. Marshall, W. McClain, R. Cooper. 2001. EFFECTS OF GYPSY MOTH DEFOLIATION ON FOREST BIRDS: AN ASSESSMENT USING BREEDING BIRD CENSUS DATA. Journal of Field Ornithology, 72, 2: 291-304.
Stewardship Overview: Formerly stable but experiencing significant decreases since 1980, particularly in West. Populations relatively widespread but deserves attention for its association with riparian and mature woodland habitats. May be of local concern in arid regions where riparian habitats are degraded or eliminated by land use practices.
Species Impact: May help control outbreaks of caterpillar pests (Bent 1940). May locally impact breeding success of host species through brood parasitism.
The black-billed cuckoo (Coccyzus erythropthalmus) is New World species of bird in the Cuculidae (cuckoo) family. It is very similar and overlaps in range with the closely related yellow-billed cuckoo.
Adults have a long, graduated brown tail and a black, slightly downcurved bill. The head and upper parts are brown and the underparts are white. The feet are zygodactylous. There is a red ring around the eye. Juveniles are drabber, and the eye ring is greenish.
|length||280–320 mm (11–12.6 in)|
|weight||52 g (1.8 oz)|
|wingspan||440 mm (17.5 in)|
|wing||132.9–140.9 mm (5.23–5.55 in)|
|tail||147.4–159.8 mm (5.80–6.29 in)|
|culmen||20.2–23.9 mm (0.80–0.94 in)|
|tarsus||21.1–24.1 mm (0.83–0.95 in)|
Their breeding habitat is edges of wooded areas across North America east of the Rockies. They nest in a low tree or shrub, sometimes on the ground, laying 2 to 4 blue-green eggs, which are incubated by both parents for 10 to 11 days. They sometimes lay eggs in the nests of other birds.
These birds forage in shrubs or trees. They mainly eat insects, especially tent caterpillars, but also some snails, eggs of other birds and berries. It is known to beat caterpillars against a branch before consuming in order to remove some of the indigestible hairs. Remaining hairs accumulate in the stomach until the bird sheds the stomach lining and disgorges a pellet in a manner similar to owls.
The call is a rapid repetitive Coocoocoo.
- BirdLife International (2012). "Coccyzus erythropthalmus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Godfrey, W. Earl (1966). The Birds of Canada. Ottawa: National Museum of Canada. p. 210.
- Sibley, David Allen (2000). The Sibley Guide to Birds. New York: Knopf. p. 268. ISBN 0-679-45122-6.
- Paulson, Dennis (2013). "Cuckoos - Tent Caterpillar Birds". BirdNote.
- "Black-billed Cuckoo". Tennessee's Watchable Wildlife. Tennessee Wildlife Resources Agency.